Steam generator



y 1942- R. SHELLENBERGER arm. 2,284,601

STEAM GENERATOR Filed July 31, 1940 2 Sheets-Sheet l INVENIORS PolfShellenberger BY agaf dward M Freeman ATTORNEY.

i- 1942 v R. SHELLENBERGER Erm. 84,601

STEAM GENERATOR Filed July 31, 1940 2 Sheets-Sheet 2 1N VENTORS lf'eShel/enberger BY 417d EdwarclMHeeman ATTORNEY.

Patented May 26, 1942 STEAM GENERATOR Rolfe Shellenberger, Westfield, N.J., and Edward M. Freeman, North Pelham, N. Y., assignors to The Babcock& Wilcox Company, Newark, N. J a corporation of New Jersey ApplicationJuly 31, 1940, Serial No. 348,772

10 Claims.

The present invention relates to the construction of furnaces forburning a slag-forming solid fuel in suspension under furnace conditionsresulting in the separation of the ash in the furnace and its depositionon the furnace fioor in the form of molten slag, and more particularlyto the construction of the floors of such furnaces.

The main object of our invention is the provision of an improved floorconstruction for furnaces of the type described which is characterizedby the maintenance of a predetermined level of the deposited slag layeron the floor, an increased resistance to erosion of the refractorportion of the floor, and generally a more durable fioor construction.

The various features of novelty which characterize our invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which We have illustrated and described several embodiments ofour invention.

Of the drawings:

Fig. l is a somewhat diagrammatic sectional elevation of a steamgenerating unit incorporating our invention; 7 v

Fig. 2 is an enlarged view of the discharge end portion of the furnacefloor shown in Fig. 1;

Fig. 3 is a transverse section partly on the line 3--3 and partly on theline 3 -3 of Fig. 2;

Fig. 4 is an enlarged view of an end portion of Fig. 3;

Fig. 5 is a section taken on the line 5--5 of Fig. 4;

Fig. 6 is an enlarged view of an intermediate portion of Fig. 3;

Fig. 7 is an end View of one of the plates of Fig. 6;

Fig. 8 is a sectional view of a modified dam construction taken on theline 8--8 of Fig.

Fig. 9 is a view similar to Fig. 8 taken on the line 9-9 of Fig. 10;

Fig. 10 is a broken transverse section taken on the line Ill-10 of Fig.8 with the refractory layer omitted; and

Fig. 11 is a section taken on the line I l-I l of Fig. 8.

In Fig. l is illustrated a high capacity high pressure steam generatingunit having a twostage furnace especially designed for burningpulverized bituminous coal in suspension which is disclosed and claimedin the copending application of Ervin G. Bailey et al., Ser. No.137,196, filed April 16, 1937. The furnace has a high temperatureprimary section I0 fired by a plurality of pulverized coal burners l Ilocated in the furnace arch l2 and discharging downwardly towards therearwardly sloping furnace floor [3. The primary furnace section ispartly separated from the lower part of a secondary furnace section l5by a partition 16 extending downwardly from the rear end of the furnacearch towards the rear end of the furnace floor. The secondary furnacesection extends upwardly to the convection heated portion of the unitwherein the heating gases pass successively across the main steamgenerating tube bank H, a superheater l8, and economizer [9.

Both the primary and secondary furnace sections have their definingwalls including the floor l3 and partition I6 cooled by steam generatingtubes. 21 extends longitudinally of the floor from the front wall of theunit to the rear end of the floor, curving downwardly around the rear orslag discharge end of the floor to a supply header 22, as shown. Thepartition I6 is defined by rows of water tubes 23 extending upwardlyfrom the header 22 between the floor tubes 2|. The spaces between theupper portions of adjacent tubes 23 are'closed by refractory means toform the partition, while the lower portions of those tubes are bent andgrouped to form heating gas passages therebetween, through the bottomsof which molten slag deposited on the furnace floor can flow down overthe curved end of the floor to the slag hopper 25, wherein it isquenched.

The furnace floor has a thick layer of suitable refractory 28, such asplastic chrome ore, held in position by metallic studs mounted on theperipheral surface of the floor tubes 2|, and extending from the frontwall of the furnace to a point near the row of screen tubes 23. Beyondthe rear end of the refractory layer, the tubes are covered with blocks26 held on the tubes, the block area terminating in a row of overhangingnose blocks 21 adjacent the rearmost portion of the bend in the tubes 2I.

. The rear end of the refractory layer is defined by a fluid cooled damstructure 30 extending the full height of the refractory layer asinstalled. The dam structure is formed in three sections, arranged inparallel planes spaced longitudinally of the floor. The first and secondsections of the dam are each formed by a row of slightly spacedrectangular steel plates 3|, double the number of floor tubes, so thateach tube has welded thereon A row of transversely spaced water tubes apair of plates 3! cut away at a lower corner to fit the tube surface. Ashort slot 32 is formed in the tube contacting edge of each plate tocompensate for temperature stresses in the plate. At intervals alongeach plate row is welded a pair of bent rods 31, uniting with the upperedge of the plates to form transversely spaced fork members in which ispositioned a long hairpin shaped tube 38 formed by superposed contactingleg portions connected at one end by a plate 39 and a cup type cap 40forming a 180 deg. return bend.

The fork members are welded to the upper tube leg only, as shown in Fig.5. A flow of a suitable cooling fluid, such as service water, ismaintained in operation through each tube 38, as indicated by the arrowsin Fig. 3.

The third section of the dam structure is formed by a row of steelplates 65 similar in construction to the plates 35, but slightlyshorter. The remaining height of this section is formed by platesections 56 of corrosion-resistant metal, welded to corresponding plates45, as shown in Fig. '7. Plastic refractory is also packed in betweenthe described sections of the dam structure. A substantial coolingeffect is thus effected by the cooling tubes 38 on the rear or dischargeend of the refractory layer, thus reducing the erosive action on therefractory and dam of the slag flowing over the dam structure.

Inoperation, the molten slag separating in the furnace chamber lcollects on the furnace floor i3 and flows rearwardly over the darnstructure onto the block'covered section of the floor tubes, through thespaces between the screen tubes, and down over the curved end of thefloor to the slag hopper. As the furnace continues in operation, theslag tends to penetrate the refractory layer, causing some of therefractory to be washed away. Eventually an equilibrium point isreached, at which time a shallow pool of slag will be supported on therefractory floor, overflowing the fluid cooled dam structure asadditional molten slag is deposited thereon. The height of the dam thusdetermines the level of the slag layer maintained on the floor.

In the modified construction illustrated in Figs. 8-11, the fluid cooleddam structure for the refractory layer 28 is located alongside the firstrow of screen tubes 23 and partly supported thereby. As shown, the damstructure is formed by a row of four superposed horizontally arrangedcontacting tubes arranged for a serial flow of a cooling fluiddownwardly therethrough by connections of certain tube ends to shortvertical The tube row is partly supported and held against the spacedscreen tubes 23 by horizontally arranged support plates 57 welded to thecorresponding tubes superjacent the floor blocks 26. Each plate 57 hasan opening 58 therein into which fits the lower bent end of an alloysteel clip bar 59 and engages therewith. The upper end of each bar 59has a horizontal L shaped extension fifi fitting across the top of thetube row and welded to the corresponding tube. 23.

With the described darn construction, the refractory layer on the floorwill extend substantially up to the tube screen and the molten slagdepositing thereon will flow over the refractory layer and dam and droponto the black covered floor between the screen tubes, flowing down overthe curved end of the floor to the slag pit 25. The fluid cooled dameffectively maintains the refractory layer in position and controls thelevel of the slag on the furnace floor.

While in accordance with the provisions of the statutes we haveillustrated and described herein the best forms of the invention nowknown to us, those skilled in the art will understand that changes maybe made in the form of the construction disclosed without departing fromthe spirit of the invention covered by our claims, and that certainfeatures of our invention may sometimes be used to advantage without a.corresponding use of other features.

We claim:

1. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to support slag in a moltencondition and discharge the same at one end thereof, a fluid cooled damextending transversely of said floor adjacent the discharge end thereofand including a transversely extending cooling tube, a verticallyarranged furnace tube extending upwardly past an intermediate portion ofthe discharge end of said floor, means for supporting said cooling tubefrom said vertically arranged furnace tube, and a layer of refractorymaterial covering said floor in front of said dam.

2. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and discharge the same at one end thereof, a rowof transversely spaced water tubes extending longitudinally of saidfloor, a fluid cooled dam extending transversely of said floor adjacentthe discharge end thereof and including a transversely extending coolingtube, plate members extending transversely of and supported on saidfloor tubes, means for supporting. said cooling tube on said platemembers, and a layer of refractory material covering said floor tubes infront of said dam.

3. A furnace for burning finely divided solid fuel under slaggingtempertaures comprising a fioor constructed to receive and support slagin a molten condition and discharge the same at one end thereof, a rowof transversely spaced water tubes extending longitudinally of saidfloor, a. fluid cooled dam extending transversely of said fioor adjacentthe discharge end thereof and including a transversely extending coolingtube, means for supporting said cooling tube on said floor tubes, and alayer of refractory material covering said floor tubes in front of saiddam.

4. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and having a slag discharge section at one endthereof, a group of transversely spaced screen tubes extending throughsaid floor adjacent the discharge end thereof and having slag dischargepassages on the floor portions therebetween, a row of transverselyspaced water tubes extending longitudinally of said floor, a fluidcooled dam extending transversely of said fioor adjacent the front ofsaid screen tubes and including a transversely extending cooling tube,means for supporting said cooling tube, and

a layer of refractory material in front of said dam.

5. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and having a slag discharge section at one endthereof, a group of transversely spaced screen tubes extending throughsaid floor adjacent the discharge end thereof and having slag dischargepassages on the floor portions therebetween, a row of transverselyspaced water tubes extending longitudinally of said floor, a fluidcooled dam extending transversely of said floor adjacent the front ofsaid screen tubes and including a transversely extending looped coolingtube, means for supporting said cooling tube from said floor, and alayer of refractory material covering said floor tubes in front of saiddam.

6. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and having a slag discharge section at one endthereof, a group of transversely spaced screen tubes extending throughsaid floor adjacent the discharge end thereof and having slag dischargepassages on the floor portions therebetween, a fluid cooled damextending transversely of said floor adjacent the front of said screentubes and including a transversely extending cooling tube, means forsupporting said cooling tube from said screen tubes, and a layer ofrefractory material in front of said dam.

'7. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a. molten condition and having a slag discharge section at one endthereof, a group of transversely spaced screen tubes extending throughsaid floor adjacent the discharge end thereof and having slag dischargepassages on the floor portions therebetween, a row of transverselyspaced water tubes extending longitudinally of said fioor, a fluidcooled dam extending transversely of said fioor adjacent the front ofsaid screen tubes and including a row of superposed transverselyextending cooling tubes contacting with said screen tubes, means forsupporting said cooling tubes from said floor and screen tubes, 50

8. A furnace for burning fine divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and having a slag discharge section at one endthereof, a group of transversely spaced screen tubes extending throughsaid floor adjacent the discharge end thereof and having slag dischargepassages on the floor portions therebetween, a row of transverselyspaced Water tubes extending longitudinally of said floor, a damextending transversely of said floor adjacent the front of said screentubes and including a transversely extending row of plate members havingupper portions formed of metal highly resistant to corrosion, means forsupporting said plate members from said floor tubes, and a layer ofrefractory material covering said floor tubes in front of said dam.

9. A furnace for burning finely divided solid fuel comprising a floorconstructed to receive slag in a molten condition and discharge the sameat one end thereof, means for burning finely divided solid fuel underconditions resulting in the deposition of slag in a molten condition onsaid floor, a row of transversely spaced Water tubes extendinglongitudinally of said floor, and a fluid cooled dam extendingtransversely of said floor adjacent the discharge end thereof andincluding a transversely extending looped cooling tube, and means forsupporting said cooling tube from said floor tubes, and a layer ofrefractory material covering said fioor tubes in front of said dam.

10. A furnace for burning finely divided solid fuel under slaggingtemperatures comprising a floor constructed to receive and support slagin a molten condition and discharge the same at one end thereof, a rowof transversely spaced water tubes extending longitudinally of saidfloor substantially throughout its length, a fluid cooled dam extendingtransversely of said fioor adjacent the discharge end thereof andincluding a transversely extending cooling tube, means for supportingsaid cooling tube above and in spaced relationship to said floor tubes,and a layer of refractory material covering said floor tubes in front ofsaid dam.

ROLFE SHELLENBERGER. EDWARD M. FREEMAN.

